fix(ssh): repair managed Windows SSH config permissions

[EhabY]

Summary

Fixes #1108. Windows files inherit their permissions from the directory they live in, so a config the extension generates under %APPDATA%\coder.coder-remote\ssh can end up readable by other accounts. OpenSSH rejects such a file with Bad owner or permissions and skips the whole Include, so one bad file blocks every Coder host, not just the one it came from.

Before each managed write, the extension locks that directory down with built-in commands and lets its files inherit from it. No Windows Script Host, ADSI, native dependency, or elevation:

Step	Command
Read the current user's SID	whoami.exe /user /fo csv /nh
Clear the directory's own grants	icacls.exe <dir> /reset
Grant that user, SYSTEM, and Administrators full control	icacls.exe <dir> /inheritance:r /grant:r <trustee>
Clear each *.conf file so it inherits the directory	icacls.exe <file> /reset

• Resetting every direct *.conf match, not only the file being written, also repairs other deployments and editors on the first connection after an upgrade. The temporary file is reset before its rename.
• Check command exit codes. Never read ACLs back or parse SDDL.
• Reject links and non-files before the repair, but tolerate an entry that disappears mid-scan: two connecting windows share the directory, and one can rename its temporary config away between readdir and lstat.
• Leave your own SSH config, and anything outside the managed directory, alone.

SshConfig takes an optional ManagedPermissions. Its absence is the marker for "not Coder-managed", which is why it has no no-op default: a default would make the extension enumerate ~/.ssh on every save on every platform. createManagedPermissions() returns undefined off Windows, so the whole repair path stays Windows-only.

What each file changes

• src/remote/windowsAcl.ts: new. The icacls repair itself, exporting WINDOWS_ACL, createManagedPermissions, and system32.
• src/remote/sshConfig.ts: adds ManagedPermissions, splits save() into named steps, and makes the temp write exclusive (wx).
• src/remote/remote.ts: passes createManagedPermissions() to the per-deployment SshConfig.
• Tests and docs: mocked and native Windows suites, CONTRIBUTING.md, and CHANGELOG.md.
• CI: adds a windows-11-arm unit job, because the repair shells out to icacls.exe and whoami.exe and Windows on ARM64 is a platform users connect from. test/env-check.ts fails that job if it ever runs under x64 emulation, which would silently make it a duplicate.
• .github/actions/setup/action.yml: moves pnpm store caching from setup-node to pnpm/action-setup. setup-node restores on an exact lockfile hash, so a dependency bump refetched the whole store on every runner; pnpm/action-setup keys on the same hash but falls back to the last store for the platform.
• pnpm-workspace.yaml: turns off the bufferutil and utf-8-validate source builds. Neither ships a win32-arm64 prebuild, so node-gyp compiled both on every cold ARM64 install. Both are dev-only and fall back to JavaScript, and platforms with a prebuild keep theirs.
• .gitattributes and .vscodeignore: a generated-file marker and a trailing newline, unrelated to the fix.

Validation

pnpm test (2,751 passed, 6 skipped), pnpm typecheck, pnpm lint, and pnpm format:check pass. Windows CI covers x64 and ARM64 on a cold pnpm store. Against OpenSSH 9.6p1, a *.conf directory aborts the whole Include on Windows, where glibc instead reads zero lines and ignores it, so the extension reports that entry rather than trying to fix it with an ACL change.

Limits

A directory-preparation failure stops the write. A single file-reset failure logs a warning and still attempts the connection, so OpenSSH may reject a fragment the repair missed. The two directory commands are not atomic: a failure after /reset can leave the directory with its parent's grants. The path and link checks stop mistakes, not an attacker racing the check.

Generated by Coder Agents on behalf of @EhabY.

[phorcys420]

is there any reason you didn't use the icacls utility or PowerShell's Set-Acl all the way to set the permissions instead of depending on JScript (assets/wsh/acl.js)?

Scripts ran by the Windows Script Host are super sketchy patterns that AVs love to flag for no reason. Spawning PowerShell is similar but less so.

[EhabY]

Simplified this a lot more by removing the pre/post ACL checks that ran to make sure everything was applied correctly. We now apply this on all runs on Windows (which takes the same amount of time as the check anyway). The only windows specific logic is in windowsAcl.ts!

[aslilac]

providing an authoritative stamp on @fioan89's behalf

[linear-code]

ENG-3335